1. Field
The example embodiments generally relate to elongate hollow structures of composite construction, including in particular tubular structures.
While the example embodiments have been devised particularly in relation to the construction of tubular structures in the form of pipes, it may also be applicable to the construction of other elongate hollow elements including tubular elements such as ducts and tubes, tubular structural elements such as shafts, beams and columns, and other tubular elements of composite construction.
2. Related Art
The following discussion of the background art is intended to facilitate an understanding of the example embodiments of the present invention only. The discussion is not an acknowledgement or admission that any of the material referred to is or was part of the common general knowledge as at the priority date of the application.
It is known to construct pipes using fibre-reinforced plastic composites. Typically, such pipes are constructed by a process in which rovings of filaments of fibre material, (such as glass fibres) are impregnated with a thermosettable resin or thermoplastic composition and wound back and forth on a mandrel to form a pipe wall structure of composite construction.
Further, there have been attempts to produce a continuous pipe by pultrusion involving a wet body of reinforcement fibres being drawn through a heated mould to cure the pipe and the pipe then wound onto a spool. Pipes constructed in this way are typically limited to lengths of about 1 km and diameters of about 100 mm.
Typically, such pipes are required to bear both hoop and axial stresses, and the construction can be a compromise between the hoop and axial stress bearing properties required for the pipe. Hoop strength can be optimised by winding the reinforcing filaments at an angle approaching 90° to the pipe axis. Axial strength can be optimised by winding the reinforcing filaments at an angle approaching the pipe axis.
The length of pipe that can be constructed in such a way is dictated by the length of the mandrel or the roll of pipe that can be transported. Consequently, the construction process is not conducive to construction of long pipes to form a transportation network for liquids and gasses; that is, pipes which are much longer than available mandrels and also pipes which are of a length to constitute a pipeline extending continuously between two distant locations, perhaps hundreds to thousands of kilometers apart.
It would be advantageous for there to be a way in which a pipeline could be constructed using a pipe constructed on a continuous basis; that is, without having to be composed of a series of pipe sections joined one to another at junctions which are likely constituted areas of weakness in structural integrity of the pipeline.
It is against this background, and the problems and difficulties associated therewith, that the example embodiments of the present invention have been developed.